The proposed program is designed to assess the suitability of using a new class of high strength stainless steels, called TRIP steels, for the fabrication of orthopedic implants. In vitro studies in physiological saline solutions will be conducted to determine the effects of a wide variety of environmental and materials variables on the corrosion resistance of TRIP steels and control materials (Type 316L stainless steel and Vitallium); particular attention will be given to crevice corrosion, pitting, stress corrosion, corrosion fatigue, and fretting corrosion. These investigations will be supported by in vivo studies which, in addition, will provide essential information about the effects of the alloys on the biological system. Biological compatibility tests will be conducted according to ASTM protocol on rats, rabbits, and dogs, and additional tests will be performed on Rhesus monkeys.